Heating pad



` 4Oct.`29, 1963 c, w, VEACH 3,108,596

HEATING PAD Filed Sept. 29, 1961 @fas/14 f.; fel/4 w 5 'I F W 1,1 l

14, c'. aurfd sgi Wien/ran.. C'fr/af A0. Veda/z United States Patent O 3,108,596 HEATING PAD Carlos W. Veach, 8921 Ashcraft, Los iinmgeles` 48, Calif. Filed Sept. 29, i961, Ser. No. 141,825 3 Claims. (til. 12S-399) The present invention relates to heating pads, and more particularly, to electrically powered heating pads that are adapted to be worn on or attached directly to the skin of a person.

It is frequently desirable to apply heat in localized areas to the surface of a persons skin. More particularly, it may be desirable to apply heat to `an extremity such as a hand or la foot to assist the body in maintaining a normal temperature therein or to apply heat to a diseased or infected area to assist in the recovery from a disease or infection. In tue latter cases, it may also be desirable to .apply suitable medicaments to the skin surface at the same time that the heat is being applied thereto. In order to accomplish these objectives, numerous attempts have been made to provide a device that can be placed on the skin for applying heat to the surface thereof. Although such devices have proved to be successful in applying heat .to the skin, they have numerous objections. For example, in devices such as a hot water bottle wherein a container is filled with a hot liquid or exothermic chemicals, they are bul-ky and/or uncomfortable and require ifrequent attention to maintain proper control of the temperature. have generally only been useful on a person who is in a reclining or sitting position. 'In so-'called electric heat ing pads, heating elements lare provided for generating the required heat. However, the source of power has heretofore had to be of a substantial nature such as a ll() volt power line. Heating pads of this nature are reasonably compart land can have the temperature thereof closely controlled. However, since relatively high voltages are employed, the dangers from electrical shock are substantial and it is necessary to employ large amounts of insulation to separate the heating elements from the skin of the person employing the heating pad. ln addition, when an electric heating pad is to be employed with a liquid medicament that is electrically conductive, the dangers from the high voltage are greatly increased and accordingly necessitate the use of water-proofing covers, etc. As a result, the foregoing heating pads 'have been unsuitable for applying heat to localized areas to the human body when the person is engaged in normal activities and particularly in certain types of locations such as between a persons legs, inside of a splint, etc.

lt is, therefore, an object of the present invention to provide a heating pad for use on the human body which will overcome the foregoing diiliculties.

t is an object to provide a heating pad that is not only more compact and easier to use, but will also be more efficient land effective in operation.

It is an object to provide an electrical heating pad that may be employed in `any :desired location such as inside of a splint or other inconvenient locations.

It is also an object to provide a heating pad that may be employed while the person is carrying on normal activities. More particularly, this is to be accomplished by providing a strip of llexible material that is arranged to form a backing member that may be secured to the surface of a persons skin. One or more electrically conductive heating elements may then be secured to the face of the backing member so that when the backing member is secured in position on the skin, the heating ele-ments will be in direct intimate contact with the skin. This will greatly increase the rate of heat transfer into As a result, devices of this nature 3,108,596 Patented Oct. 29, 1963 ICC the skin. This will in turn drastically reduce the amount of power required to maintain va given temperature to the point where it may be economically obtained from -a battery worn or carried by the patient. The heating elements preferably comprise one or more conductive wires having a low resistance. As a result, for any given power requirement the voltage drop across the heating elements may be made so low, for example, live volts or less, that the danger of electrical shock is eliminated. As a consequence, the insulation may be eliminated and the heating elements placed in direct Contact with the surface of the skin. in addition, if desired, any suitable liquids or medicaments may be applied to the skin and/ or in the immediate vicinity of the heating elements without in any way increasing the likelihood of electrical shock.

These and other features and advantages of the present invention will become readily apparent from the following detailed description thereof particularly when taken in connection with the accompanying drawings wherein like numerals refer to like parts and wherein:

FIGURE l is a top plan view of a heating pad embodying the present invention;

'FIGURE 2 is .a bottom plan view of the heating pad in FIGURE l;

FlGURE 3 is a longitudinal cross sectional view taken substantially along the plane of line 3-3 in FIGURE 1 and looking in the direction o-f the arrows thereon and showing the heating pad secured to the surface of a layer of skin;

FIGURE 4 is a top plan View of ia heating pad ernbodying a Imodilied form of the present invention;

FIGURE 5 is a longitudinal cross sectional view of the heating pad of FIGURE 4 taken substantially along the plane of line 5-5 in FIGURE 4 and looking in the direction of the arrows thereon; and

F lGURE 6 is a schematic diagram showing the heating pad operatively interconnected with an alternative source of power.

Referring to the drawings in more detail and particularly to FlGURES l, 2 `and 3, the present invention is particularly adapted to be embodied in a heating pad 10 that may be mounted on the surface 12 of a layer of skin on the human body. lIn the present instance, this heating pad 1G comprises `a backing member 14 which may be formed rxfrom a strip of suitable material. The material is preferably relatively flexible so as to be capable of always conforming to the distortions of the skin while adhering thereto. For example, it may comprise a piece of plastic, cloth or similar material and it may or may not be porous. The backing member 114 which will dene the size and shape ofthe heating pad 1l), may be of any desired size and shape suitable for the use to which it is to be put. Preferably the backing member 14 is approximately equal to or slightly larger than the area which it is intended to heat.

.The heating pad 16' may be secured in position by any suitable means such as employing a strip of adhesive tape ete. However, in the present instance an opening 16 is provided in each end of the pad 101. This opening 16 is formed by a hollow rivet 18 that extends completely through the backing `member 14 iand has .the opposite ends thereof headed to thereby form eyelets. Thus, an elastic band or similar device having hooks on the ends thereof may be attached to the rivets 18 and extend around the body member to .thereby secure lthe pad 10 in position. In addition, or alternatively, a layer 20 of pressure sensitive Iadhesive may be formed on the inner surface of the backing member 14. Thus, when the heating pad 1li is in operative position, the layer 20 of adhesive will be in engagement with the surface 12 of the skin and accordingly will retain the pad 10 in position thereon.

y In order to generate the required heat for maintaining the required temperature in the skin, one or more heating elements 22 may be provided on the backing member 14. The heating elements 22 are preferably disposed on the inner surface of the backing member 14 whereby they may be disposed in direct intimate contact with the surface 12 of the skin. In the present instance, the heating element 22 comprises a conductive wire 24 which is formed into a suitable pattern such as a series of undulations. The wire 24 may be secured in position Vby any suitable means such 4as dry adhesive bonding.` However, in the present instance, the wire 24 is merely compressed into the layer 20 of pressure sensitive adhesive on the inner surface of the vbacking member 14 so as to be permanently secured thereto. The opposite ends 23 of :the wire 24 forming the heating element 22 may extend through the backing member 14 and thereby form means suitable for interconnecting with a suitable source of power. A1- though any suitable connector means may be provided, in this embodiment a pair of suitable snap fasteners 26 or similar devices lare secured to the backing member 14 so that the ends 23 of the wire 24 may be secured thereto. The fasteners 26 are in turn adapted to be interconnected with a suitable source of power such as a battery 25.

Although the heating elements 22 may be formed in any suitable manner, in the present instance they comprise a wire 24. The wire 24 which may consist of any suitable electrically conductive materials preferably of copper or a similar material having a low specific resistivity. Thus, even though the length of the wire 24 may be long enough to insure :the heating element covering substantially the entire area of the heating pad 10, the overall resistance of the heating element 22 will be relatively low, for example, on the order of a few ohms. Since the `amount of power provided by a heating element is determined by the square of the voltage drop thereacross divided by the resistance thereof, it will be readily apparent that by employing a small resistance a small vol-tage may be employed. For example, with a resistance on the order of 2 to 4 ohms and a voltage of about volts, va power output of from about 5 watts to about l5 watts may be obtained. Itis, of course, readily apparent that such a low vol-tage is below the critical level that produces electrical shock or burning and accordingly the Aheating elements may be in direct contact with the surface 12 of the skin. As a consequence, the heat transfer from the heating element 22 into the skin will be very eicient. Thus, a small number of Watts will -bc adequate to maintain the temperature of small areas. It may, therefore, be seen that it is now possible -to employ-a relatively small battery 25 for energizing the heating pad for extended periods. This will in turn permit a person to carry on normal activities while utilizing Ithe present hea-ting pad 10.

As 'an alternative, Vthe heating pad 28 of FIGURES 4 to 6 inclusive may be employed. In this embodiment aV backing member 30 is provided which has a size and shape corresponding to the area that is tol be heated. The backing member 30 may consist of any suitable material; however, it is preferably a cloth or similar material that is sufficiently porous to permit moisture to pass therethrough.

In order to secu-re the heating pad 28 in position, the opposite ends of the backing member 30 may be provided with eyelets 32 that are formed by hollow rivets 34. These eyelets 32 may be adapted to receive suitable hook fastening means on the opposite ends of an elastic band that extends around a body member. In addition, or alternatively, a layer of pressure sensitive adhesive may be provided on the inner surface of the backing member '30 so as to engage the surface of the skin and adhere thereto and thereby `secure the pad 28 in position.

An absorbent pad 36 consisting of a material such as -cotton batting, gauze, etc. may be provided on the backing member 30. In addition, an outer cover 318 may extend the full length of the backing member 30. The op- Y posite ends of the cover 38 are secured on the backing member Se by any suitable means such as bonding or by the rivets 34. It may thus be seen that the pad 36 will be secured in position between the cover 38 and the backing member Btl.

In order to generate the required heat, one or more heating elements 4l) similar to the heating elements 22 in the rst heating pad lll may be provided on the surface of the backing member 30. In the present instance, this heating element 4i? comprises a conductive wire 42 which is formed into an undulating pattern and is secured thereto by any suitable means such as an adhesive. The wire 42 may consist of any suitable material, however, it preferably comprises a material having va low specific resistivity such as copper. Thus, ythe overall resistance of the heating element 40 will he relatively low, for example, on the order of a few ohms. The opposite ends 43 of the wire v42 forming the heating element 46 preferably extend through the backing member 30 and terminate with connector means 45 which are adapted to be interconnected with a suitable power source. In the present instance the wire 42 terminates in the form of a couple of connector pins 44. These pins 44 are in turn adapted to plug into a pair of sockets 46 interconnected with the secondary of a step down transformer 48.

Since the overall resistance of the heating element 4U will be very low, the voltage drop thereacross will also be very small. As a consequence, the heating element may be placed in direct contact with the surface of the skin without any danger of electrical shock or execution occurring therefrom. In addition, if so desired, a liquid such as plain Water or a solution containing a suitable medicament may be absorbed in 4the pad 36. This liquid may then traverse the porous backing member 30 and cause the heat being applied to the skin to be accompanied by a suitable moisture. It is, of course, readily apparent that even though the moisture increases the electrical conductivity on the skin surface, the voltage will be so low -that there isstill no danger of an electrical shock or burn.

`It may thus be seen that a heating pad has been provided that is very compact land may be used in any desired location on the human body. More particularly, it may be used inside of a bandage or cast without in any way interfering with the operation thereof. Since the power supply has a voltage that is below the critical level that produces shock or burning, there is no danger from such injuries even though there is little `or no insulation between .the heating element and the skin. In addition, since the heating elements are disposed to insure a more eicient heat transfer, they may be energized by means of batteries whereby .the heating pad may be employed for heating areas even while the wearer is engaged in normal activities. Although only a limited number of embodiments and applications have been disclosed, it will be readily apparent to those skilled in the art that numerous changes and modifications may be made thereto without departing from the spirit [of the invention. Accordingly, the foregoing `description and drawings are for illustrative purposes only and are not intended to limit the invention which is defined only by the claims which follow.

What is claimed is:

l. Means for electrically supplying a predetermined amount of heat directly to a limited area on the external surface of a layer of skin, said means comprising the combination of:

a strip of flexible material arranged to form a backing member having a length and width that correspond to said area, said strip being adapted to be positioned on said skin with a surface thereof disposed in intimate contact with said external surface of said skin,

means on said backing member for retaining said member positioned on said layer of skin with the surface thereof forced against said external surface so as to 3. Means for electrically supplying a predetermined amount of heat directly to a limited area on the external surface of a layer of skin of a person, said means comprising the combination of be maintained in substantially direct contact therewith,

an electrical heating element consisting of an electrically conductive wire having a low specific reing of said skin.

sistance that will provide an overall resistance of said a strip of liexible porous material arranged to form heating element that is low enough to permit the abacking member havingalength and width that corpredetermined amount of heat to be generated upon respond to said area, said strip being adapted to be the application of a voltage across said element that positioned on said skin of a person with a surface is below the critical value for producing an electrical thereof disposed in intimate contact with said exshock or burning of said skin, ternal surface of said skin, adhesive means on said backing member for maintainan absorbent pad disposed on the opposite side of said ing in a predetermined pattern with at least a porstrip for maintaining said porous strip moist, tion of said element being exposed for disposition a cover disposed over said pad for preventing the loss in direct intimate contact with the surface of said of moisture into the atmosphere, skin when said backing member is disposed thereon, a film of pressure sensitive adhesive on said surface and of said backing member for being disposed on said means for interconnecting said heating element with skin surface, said film being effective for retaining a source of electrical power having an electrical posaid member positioned on said layer of skin in tential that is below said critical level for producing response to being forced thereagainst with said surelectrical shock or burning of said skin. 2() faces maintained in substantially direct Contact with 2. Means for electrically supplying a predetermined each other, amount of heat directly to a limited area on the external an electrical heating element consisting of an electrisurface of a layer of skin of a person, said means comcally conductive wire having a low specific resistance prising the combination of that will provide an overall resistance of said heata strip of flexible material arranged to form a backing ing element that is low enough to permit the premember having a length and width that correspond determined amount of heat to be generated upon the to said area, said strip being adapted to be positioned application of a voltage across said element that is on said skin of said person with a surface thereof below the critical value for producing an electrical disposed in intimate contact with said external surshock 0r burning 0f Said skin, face of said skin, said wire being disposed in an undulating pattern on a ilm of pressure sensitive adhesive covering at least the Surface 0f Said hacking Ineniher and embedded in a portion of said surface of said backing member for Said fdrn 0f adhesive fOr being maintained in Said being disposed on said skin surface, said nlm being iiirn in Said undulating Pattern, at least a Portion 0f effective for retaining said member positioned on Said eiernent being eXPOSed thrnu'h Said iiirn 0f adsaid layer of skin in response to being forced therehesive for disposition in direct intimate contact with against with said surfaces maintained in substanthe Surface 0f Said Skin When Said backing rnernber tially direct contact with each other, is disposed thereon, and an electrical heating element consisting of an electrically means fOr interconnecting Said heating element With a conductive wire having a low specic resistance that source of electrical power having an electrical powill provide an overall resistance of said heating ele- 40 tential that is below said critical level for producing ment that is low enough to permit the predetermined electrical shock or burning of said skin. amount of heat to be generated upon the application of a voltage across said element that is below the References Cited in the file 0f thiS Patent critical value for producing an electrical shock or burning of said Skin UNITED STATES PATENTS said wire being disposed in an undulating pattern on 1,594,053 Evans July 27, 1926 the surface of said backing member and embedded 2,028,889 Baddour J an. 28, 1936 in Said lm of adhesive for being maintained in said 2,423,196 MacKendrick July l, 1947 film in said undulating pattern, at least a portion of 2,488,793 Amerkan Nov. 22, 1949 said element being exposed through said film of ad- 2,573,791 Howells Nov. 6, 1951 hesive for disposition in direct intimate contact with 2,715,674 Abbott et al Aug. 16, 1955 the surface of said skin when said backing member is 2,802,091 MacKendrick Aug. 6, 1957 disposed thereon, 2,808,352 Coleman et al Oct. 1, 1957 a power source for being carried by said person, and 2,952,761 Smith-Johannsen Sept. 13, 1960 hmeans for interconnecting said power source with said 2,993,979 Hornsby July 25, 1961 eating e ement for supplying electrical ower thereto at an electrical potential that is beloii said FOREIGN PATENTS critical level for producing electrical shock or burn- 809 Great Britain Mar. 18, 1872 

1. MEANS FOR ELECTRICALLY SUPPLYING A PREDETERMINED AMOUNG OF HEAT DIRECTLY TO A LIMITED AREA ON THE EXTERNAL SURFACE OF A LAYER OF SKIN, SAID MEANS COMPRISING THE COMBINATION OF: A STRIP OF FLEXIBLE MATERIAL ARRANGED TO FORM A BACKING MEMBER HAVING A LENGTH AND WIDTH THAT CORRESPOND TO SAID AREA, SAID STRIP BEING ADAPTED TO BE POSITIONED ON SAID SKIN WITH A SURFACE THEREOF DISPOSED IN INTIMATE CONTACT WITH SAID EXTERNAL SURFACE OF SAID SKIN, MEANS ON SAID BACKING MEMBER FOR RETAINING SAID MEMBER POSITIONED ON SAID LAYER OF SKIN WITH THE SURFACE THEREOF FORCED AGAINST SAID EXTERNAL SURFACE SO AS TO BE MAINTAINED IN SUBSTANTIALLY DIRECT CONTACT THEREWITH, AN ELECTRICAL HEATING ELEMENT CONSISTING OF AN ELECTRICALLY CONDUCTIVE WIRE HAVING A LOW SPECIFIC RESISTANCE THAT WILL PROVIDE AN OVERALL RESISTANCE OF SAID HEATING ELEMENT THAT IS LOW ENOUGH TO PERMIT THE PREDETERMINED AMOUNT OF HEAT TO BE GENERATED UPON THE APPLICATION OF A VOLTAGE ACROSS SAID ELEMENT THAT IS BELOW THE CRITICAL VALUE FOR PRODUCING AN ELECTRICAL SHOCK OR BURNING OF SAID SKIN, ADHESIVE MEANS ON SAID BACKING MEMBER FOR MAINTAINING IN A PREDETERMINED PATTERN WITH AT LEAST A PORTION OF SAID ELEMENT BEING EXPOSED FOR DISPOSITION IN DIRECT INTIMATE CONTACT WITH THE SURFACE OF SAID SKIN WHEN SAID BACKING MEMBER IS DISPOSED THEREON, AND MEANS FOR INTERCONNECTING SAID HEATING ELEMENT WITH A SOURCE OF ELECTRICAL POWER HAVING AN ELECTRICAL POTENTIAL THAT IS BELOW SAID CRITICAL LEVEL FOR PRODUCING ELECTRICAL SHOCK OR BURNING OF SAID SKIN. 